marshmallow ass Share definition Flag When you have a rear end that's so soft, gropeable, and fat that each buttcheek feels like giant, smooth marshmallows. "I could use your marshmallow ass as a memory foam pillow all night long!" marshmallow ass by Meaty Man October 7, 2016 0 0 Get merch Get the marshmallow ass mug. Buy Now — $32.95 See more merch